1. Field of the Invention
This invention relates to gels prepared from novel anionic block copolymers of mono alkenyl arenes and conjugated dienes.
2. Background of the Art
The preparation of block copolymers of mono alkenyl arenes and conjugated dienes is well known. One of the first patents on linear ABA block copolymers made with styrene and butadiene is U.S. Pat. No. 3,149,182. These polymers in turn could be hydrogenated to form more stable block copolymers, such as those described in U.S. Pat. No. 3,595,942 and U.S. Re. Pat. No. 27,145. Such polymers are broadly termed Styrenic Block Copolymers or SBC's.
SBC's have a long history of use as adhesives, sealants and gels. A recent example of such a gel can be found in U.S. Pat. No. 5,879,694. With the increased use of oil gels, the need for improved properties (expressed in terms of higher tensile strength and higher elongation) exist. Such gels may also be used, for example, as a water proofing encapsulant/sealant for electronics and in wire and cable applications. Many gels have deficiencies in their properties, such as resistance to oil bleed-out. Accordingly, it would be helpful to have gels which when molded have a smoother surface appearance since gels are often sold as consumer products without covers for example as shoe inserts.
Now a novel anionic block copolymer based on mono alkenyl arene end blocks and conjugated diene mid blocks and having a predominately linear structure prepared with an alkoxy silane coupling agent has been discovered and is described in copending, commonly assigned U.S. patent application Ser. No. 60/385,663, entitled “Process for Preparing Block Copolymer and Resulting Composition”. Methods for making such polymers are described in detail in the above-mentioned patent application. Patentees have found that these new polymers will allow the preparation of improved oil gels. In particular, the gels have improved molding appearance with equivalent mechanical properties resulting in improved oil gels.